O'Reilly logo

The Core iOS Developer’s Cookbook, Fifth Edition by Rich Wardwell, Erica Sadun

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Monitoring the Battery State

You can programmatically keep track of the battery and charging state. APIs enable you to know the level to which the battery is charged and whether the device is plugged into a charging source. The battery level is a floating-point value that ranges between 1.0 (fully charged) and 0.0 (fully discharged). It provides an approximate discharge level that you can use to query before performing operations that put unusual strain on the device.

For example, you might want to caution your user about performing a large series of mathematical computations and suggest that the user plug in to a power source. You retrieve the battery level via this UIDevice call, and the value returned is produced in 5% increments:

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required